This invention relates generally to an improvement in roller and roller assemblies for use in idler systems such as belt conveyer idler systems.
Conveyer manufacturers are presently constructing idlers (for example, transporting idlers, troughing idlers, return idlers, and impact idlers) using steel or rubber rollers or plastic shells, each of which makes use of lubricated balls or roller bearings. The prior art designs are typically hollow in design rather than solid, or, in some cases, the roller is constructed of a solid shell portion with a foam innercore. Examples of some prior art idler rollers and roller assemblies are found in the following U.S. Pat. Nos.: 3,406,438--D. C. Reilly; 3,711,912--F. Teske et al; 3,888,131--C. M. Reid; and 4,440,295--P. J. Blackwood-Murray. The patent to Reilly shows a plastic-metal belt conveyer roller assembly. The roller appears to be hollow with a rigid, plastic shell, such as polyvinyl chloride. The Blackwood-Murray patent discloses an idler roller having an impact resistent synthetic plastic shell and a foam core. The Reid invention does not necessarily refer to rollers themselves but to a covering for idler rollers; the Reid covering being made preferrably of polyurethane elastomer. Teske appears to teach a roller constructed of a central core made of foam polyurethane and a hard casing made of cross-linked polyurethane.
In addition to the prevalent, shell type designs of the prior art, the roller assemblies of the prior art designs are outfitted with lubricated ball or roller bearings.
These known prior art roller assemblies are given to certain maintenance problems. All of the rollers require lubrication and maintenance of grease seals; such frequent lubrication resulting in high maintenance costs. Grease leakage due to over-lubrication or worn grease seals provides glue for stickage of conveyed material which results in buildup and impairs the rotation of rollers. Rollers lock-up due to material contamination of highly precision bearings; such lock-up resulting in holes being worn in the idler rolls by the continuously moving belt, which in turn also damages the conveyer belt. Rust and corrosion of metal components is a problem for prior art systems used outdoors. Furthermore, due to the relatively narrow thickness of the outer shells, conventional rollers tend to wear fast.